This chapter is from the book

This chapter is from the book

Authors of Web content require a means of managing that content and uploading
it to the server. One of the protocols used for this purpose is DAV (Document
Authoring and Versioning). DAV enables users and applications to publish and
modify Web content. In this hour, you will learn

What publishing solutions are available

How to build and configure the DAV extension for Apache

How to configure DAV clients to work with Apache

The Need for a Publishing Protocol

In the early days of the Web, the Webmaster or system administrator
traditionally edited the content of Web pages directly in the system hosting the
Web site. The Webmaster logged in to the system remotely, via the telnet or rsh
protocol, and used conventional text editors to edit the HTML code.

As the Web became more popular, several factors described in the following
sections made this approach impractical in many situations.

Windows as a Web Server Platform

A number of Windows-based Web servers appeared, such as Microsoft Internet
Information Server. Although not necessarily more robust or secure than their
Unix counterparts, these Web servers were definitely easier to use and set up
and quickly grew in popularity. However, Windows servers lacked extensive remote
access capabilities, and content was copied by hand or by sharing folders in the
same local area network.

Separation of Tasks

As Web sites grew in complexity and refinement, a series of new roles
emerged. The Webmaster was in charge of administering the Web server, analyzing
the logs for errors, updating the software, and so on. Web programmers dealt
with providing dynamic features in the Web site, such as personalization,
processing forms, and content searching. Designers and editors provided content
and graphics for the Web site. This separation of tasks required access
restriction policies and easy-to-use methods for updating the Web site content
by nontechnical individuals. The tools for generating Web content evolved from
simple text editors to sophisticated publishing tools, closer to word processors
in features and ease of use.

These tools run on the desktop machine and need a way to upload their content
to the Web server.

Web Hosting

Eventually, third-party companies started providing Web-hosting services to
corporate customers. Internet service providers and Internet portals provided
personal home pages to their users. This increased even more the need for a
secure, standard, easy-to-use mechanism for transferring and updating Web
pages.

Earlier solutions to this problem were based on different protocols and were
not entirely satisfactory. These solutions included:

FTP protocol: Files could be uploaded and deleted using the File
Transfer Protocol (FTP) protocol. This was cumbersome for system administrators,
who needed to maintain and configure a separate server and user database, and
for users, who required an additional tool to upload their changes. The software
providers started integrating FTP clients with their publishing products to make
it easier for the end user.

File uploads via forms: Some hosting providers allowed clients to
upload pages via a form interface. This allowed upload of only one file at a
time, and thus was suitable only for simple Web sites such as home
pages.

File mirroring software: Tools such as rsync and custom mirroring
scripts can compare a local repository with a remote one and make the necessary
changes to synchronize them. These are command-line tools commonly used by
administrators and advanced developers.

HTTP PUT: This method was eventually introduced in the
HTTP specification and allowed clients, such as Netscape Composer, to upload
files directly to the server.

Proprietary protocols: This includes protocols such as those from
the Microsoft FrontPage publishing tool. They required modifications to the
server to support these protocols.

In summary, the existing solutions were difficult to use and administer,
nonstandard, and usually required setting up a special, separate server. A new
protocol based on HTTP was developed to address these shortcomings: Distributed
Authoring and Versioning, also known as DAV or WebDAV. This hour covers the
installation and configuration of the DAV protocol and mentions Microsoft
FrontPage server extensions because of their popularity.